Direct access storage devices of the type commonly referred to as disc drives employ a rotating disc or a plurality or stack of rotating discs as a storage media. In such devices, one or more discs are mounted for rotation about a fixed vertical axis in proximity to an access mechanism which carries an array of read/write heads on a supporting mechanism. The access mechanism usually includes a linear motor mounted on an extension which is radially positioned from the centerline of the recording discs to facilitate movement of the read/write heads radially of the disc surfaces.
The disc pack is rotated at a constant speed while the read/write heads are moved to discrete positions along a radius of the discs so data can be recorded and read back from data tracks forming concentric circles on the disc surface. In present day devices, these data tracks are very closely spaced, thereby requiring that the read/write heads be positioned with great accuracy for recording and retrieving the data.
The disc packs are removable and replaceable on a disc drive. The packs have centering and support surfaces which contact cooperating surfaces on a spindle of the disc drive. The spindle is power driven for rotation of the disc pack at a constant speed. Because the disc packs are removable and replaceable, the interfitting surfaces on the spindle and the disc pack must be located and machined with precision on each disc drive because the packs are also interchangeable between drives. In the past, such spindles have generally been formed as a single piece structure requiring the total spindle body to be hardened and machined. It is the purpose of this invention to provide an improved and more economical spindle assembly for use in disc drives.